www.phidot.org

Current build is dated January 28, 2007. If you're using anything time-stamped before June, 2006, you really should upgrade. The most recent addition is mixture models were added to the occupancy data type and the robust design occupancy data type. You can access these models from the "Change Data Type" choice under the PIM menu when you open up the basic data types.

You can grab MARK in all the usual places, including

http://www.phidot.org/software/mark/download/setup.exe